Beyond Hot Cracking: Impact of Minor Elements on a Novel Ni-Based Superalloy for Additive Manufacturing

Minor elementsMinor elements such as boronBoron, carbon, and zirconium have been used for many decades to improve the high-temperature properties of Ni-based superalloysNi- based superalloy. However, the advances in additive manufacturingAdditive manufacturing technologies and the resulting popularity have put these elements in a bad light since they have been identified to be the major cause of hot crackingCracking problems. This study covers the influence of these elements on hot crackingCracking, but its focus lays on their impact on strain-age crackingStrain-age cracking (SAC) and mechanical propertiesMechanical properties. The impact of these elements has been studied in four versions of a high tantalumTantalum-containing novel Ni-based superalloyNi- based superalloy that is being developed for Powder Bed Fusion-Laser Beam/Metals (PBF-LB/M). Increasing the boronBoron content from 0.007 to 0.019 wt.% leads to severe hot crackingCracking, but reduces SAC during the heat treatmentHeat treatment. The addition of 0.022 wt.% zirconium does not increase the hot crackingCracking susceptibility but increases the SAC susceptibility. The variation of minor elementsMinor elements does not affect room temperature tensile propertiesTensile properties, but an increased zirconium and boronBoron content increases the elongation at fracture at 850 °C. The alloys with a low boronBoron and medium boronBoron content show a high notch-sensitivity during stress-rupture tests, which leads to failure in the fillet of the sample. Only the boronBoron and zirconium alloys were able to achieve valid stress-rupture results.